1. Field of the Invention
The present invention relates to a variable valve gear for an internal combustion engine wherein a connecting pin is moved to connect or disconnect two rocker arms to or from each other, thereby causing both arms to swing integrally or causing one of the rocker arms to swing and the other rocker aim to stop.
2. Description of Background Art
Valve gears for internal combustion engines are known. See, for example, JP-A No. 2011-202625 wherein two intake-side rocker arms are configured to be connectable to each other by means of a connecting pin that is movable back and forth by an actuator. In addition, see, for example, JP-A No. 2002-122007 wherein an intake valve is directly opened and closed by a camshaft and an exhaust valve is opened and closed by a rocker arm that is driven by the camshaft.
In JP-A No. 2011-202625, the connecting pin inserted into the two intake-side rocker arms is provided at an upper portion of the rocker arms. For this reason, the intake-side rocker arms protrudes upwardly and an upper end of the valve gear is raised, leading to increases in the total height and size of the internal combustion engine.
Even in the case where the variable valve gear including the rocker arm stopping mechanism as disclosed in the above-described JP-A No. 2011-202625 is employed in the valve gear, such as disclosed in the JP-A No. 2002-122007, wherein the intake valve is directly driven by the single camshaft and the exhaust valve is driven through the rocker arm, there is a need for a small compact layout using a limited amount of space in a cylinder head.
Furthermore, in JP-A No. 2011-202625, when a pushrod of the actuator is moved back for releasing the connection between the two intake-side rocker arms, the connecting pin returns quickly under the elastic force of a spring, which might create a knocking sound.